1. FIELD OF THE INVENTION
The present invention generally relates to wells and, more particularly, to an improved method and apparatus for cleaning and treating wells.
2. PRIOR ART
Various types of apparatus and methods have been used to clean and treat wells, such as oil and gas wells and the like. In many instances scale, sludge and tar must be periodically removed from the interior of the well casing before and during production to prevent plugging and restriction of the perforations and well flow. Such methods and apparatus generally are expensive and utilize components which periodically have to be replaced at substantial cost. Moreover, many such cleaning methods and apparatus are not very efficient and are ill-suited for other forms of well treatments such as formation flow stimulation.
Other cleaning methods utilize specialized equipment employing high pressure, high volume (flow rate) steam treating techniques and the like which involve undue agitation of the soil and sand around the casing perforations, thereby substantially increasing the necessity for sand bailing; that is, the removal of sand newly and excessively loosened in the formation by the treatment, which sand enters the casing with the oil.
Most present secondary recovery systems employ pumps located within the well casing to pump oil to the surface. With time, the perforations in the casing become clogged with tar, scale, etc., as does the inside of the well casing. Present practice involves periodically removing the entire pump assembly, locating a cleaning tool within the casing to scrub the interior, and re-inserting the pump assembly within the casing. This is a long and costly process.
Accordingly, there is a need for a simplified method and apparatus capable of inexpensively, rapidly and efficiently cleaning a well and of also stimulating formation oil flow without increasing the risk of causing large intrusions of newly loosened formation sand and tar into the well.